The aims of the project are: i. to assess selected aspects of reliability of DSM and ICD substance use and non-substance use psychiatric diagnoses with a non-clinician-clinician, test-retest design using state-of-the-art structured and semi-structured assessment tools among 100 drug users who are risk for other psychiatric disorders. Trained non-clinicians will use the WHO/ADAMHA Composite International Diagnostic Interview (CIDI) for substance use diagnoses; the clinicians will use the WHO/ADAMHA Schedules for Clinical Assessment in Neuropsychiatry (SCAN) for all diagnoses. ii. to assess certain aspects of validity of the DSM and ICD substance use and non-substance use psychiatric diagnoses derived from the CIDI/SAM and SCAN by comparing the data from these single source interviews to modified LEAD standard diagnoses. Expert clinicians will determine DSM and ICD "expert/all sources" diagnoses based on reviewing several sources of information including: videotaped recording of the CIDI/SAM and SCAN interviews, records of interviews with collateral sources, results from questioning respondent about discrepancies between the two interviews, urine drug screen results and medical record data iii. to evaluate reasons for differences in responses during the two diagnostic interviews through a Discrepancy Interview Protocol. iv. to compare results of this study with those of a current study on the reliability of substance use diagnoses. v. to funnel information from this study to the CIDI and SCAN Editorial Committees at WHO and to the authors of the SAM to help them refine these diagnostic instruments. In early phases of the project, the Applicant will work with authors of the SAM to insure adequate coverage of the latest DSM-IV and ICD-10 substance use disorders criteria, including the specific withdrawal syndromes and substance induced mental disorders.